Halogenated polymers, including the polychloroprene polymers such as neoprene, have been commercially available for many years and have been used extensively in the roller industry and the rubber industry in general. Elastomers prepared from these polymers possess a combination of properties which make them useful for many rubber applications. Among their desirable properties are resistance to oil, solvents and chemical reagents, good aging characteristics and excellent cured physical properties.
In the past, efforts have been made to improve the electrical conductivity of polychloroprene and other elastomers by incorporating into the elastomers highly structured carbon blacks, conductive plasticizers and/or other electrically conductive additives. However, the use of such conductive additives has not been without disadvantages. For example, the use of structured carbon black at the levels required for desired conductivities restricts the ability to obtain other desired properties and makes it impossible to prepare non-black electrically conductive articles. The use of carbon black and/or other powdered additives makes it difficult to obtain materials having a high degree of uniformity in conductivity. The use of conductive plasticizers has generally resulted in a degradation of physical properties and lack of permanence of conductivity.
Recently, urethane elastomers having electroconductive properties have been prepared by incorporating quaternary ammonium salts into the elastomer formula. However, the quaternary ammonium salts that have been found to be useful are relatively expensive and the resistivities of the elastomers obtained are generally unacceptably high. Furthermore, some of the quaternary ammonium salts are potentially hazardous to workers and their use requires the use of a solvent system so that the elastomers can only be made in the form of films or sheets.
The need still exists for electrically conductive elastomers having the good physical properties of halogenated polymers, such as neoprene.